What is the purpose of using CFU in microbiology?

The use of Colony Forming Units (CFU) in microbiology serves primarily to estimate the number of viable microorganisms present in a sample. This measurement is crucial because it provides insight into the microbial count that can grow and form colonies under specific culture conditions. CFUs are determined by plating a diluted sample on an appropriate growth medium and counting the distinct colonies that develop after incubation. Each colony is assumed to arise from a single viable microorganism, thus allowing for an estimation of the original population density in the sample.

In contrast, while identifying specific types of bacteria can be an important aspect of microbiological study, it typically involves additional methods such as biochemical tests or molecular techniques, rather than just the CFU count. Measuring pH is a different parameter that reflects the acidity or alkalinity of a solution, which does not relate to colony counting. Additionally, determining the size of microbial colonies involves assessment of growth characteristics but does not correlate to the quantitative measure provided by CFUs. Therefore, CFU is strictly a metric for estimating viable microbial presence in a sample.